1. Field of the Invention
The present invention relates to an image forming apparatus using a liquid as a recording material.
2. Description of the Related Art
For example, an inkjet recording apparatus is used in an image forming apparatus such as a printer, a facsimile machine, a copy machine, a multi-function peripheral machine, etc. The inkjet recording apparatus records or forms an image on a recording medium such as a recording paper by injecting droplets of ink as a recording liquid onto the recording paper. The recording medium on which an image is recorded by the inkjet recording apparatus may include various materials such as a recording paper, a transfer paper, a transfer material, a recording material (a material on which recording is performed), etc. Recording by the inkjet recording apparatus may be used in the same meaning as image forming, picture printing, character printing, image printing, etc.
The inkjet recording apparatus normally has a problem in that a recording error occurs due to malfunctioning of a recording head, which injects droplets of ink pressurized in a pressurizing chamber from a nozzle onto a recording paper. The recording error occurs in the recording head due to an increase in a viscosity of ink, solidification of ink, adhesion of dusts, interfusion of bubbles in ink, etc. An increase in ink viscosity and solidification of ink occur due to evaporation of solvent contained in ink at the nozzle.
In order to prevent such a problem associated with the recording head, a cap member is provided to the recording head in order to seal the nozzle when recording is not performed. A wiping member may also be provided to clean a nozzle formation surface. Further, a dummy recording discharge receiver may be provided to receive discharged droplets of ink, which do not contribute to recording. The cap member does not only serve as a lid of the nozzle to prevent desiccation of ink but also serves as a suction member to suction the nozzle. That is, the cap member seals the nozzle formation surface and pulls ink out of the nozzle by using a negative pressure introduced by a suction pump in order to eliminate clogging of the nozzle.
The forcible ink suctioning process to eliminate clogging in the recording head is referred to as a cleaning operation or maintenance. The cleaning operation is carried out when restarting a recording operation after a long time stop period of the inkjet recording apparatus. The cleaning operation may be performed at a predetermined time interval during a recording operation. The cleaning operation can be performed by operating a cleaning switch when a user finds malfunctioning of the recording head. The cleaning operation may also be performed at the time of replacing a cartridge. In the cleaning operation, ink is pulled out of the recording head, and, thereafter, the nozzle formation surface (a surface forming the nozzle) of the recording head is wiped by a wiping member made of an elastic material such as rubber. Additionally, during a recording operation, a dummy recording discharge is performed at a desired timing.
A waste liquid (waste ink) ejected from the recording head into the cap member is stored in a waste liquid tank by being moved by a suction pump. Generally, a porous material is accommodated in the waste liquid tank to retain the waste liquid by being absorbed by the porous material.
The waste liquid tank accommodating the waste liquid absorbing material has a capacity to retain an entire amount of waste liquid generated during a service life of the recording apparatus. Accordingly, a relatively large capacity is required for the waste liquid tank, and such a waste liquid tank is arranged, for example, at a bottom of the recording apparatus while occupying a large area of the bottom. Thus, there is a problem in that the waste liquid tank may limit a miniaturization of the recording apparatus.
Thus, there is suggested an image forming apparatus equipped with a replaceable waste liquid tank (for example, refer to Patent Document 1). Additionally, there is suggested a liquid injection apparatus having means for memorizing an amount of liquid discharged into a waste liquid recovery container, wherein the memory is reset when the waste liquid in the waste liquid recovery container is collected to a waste liquid tank (for example, refer to Patent Document 2).    Patent Document 1: Japanese Laid-Open Patent Application No. 2005-088419    Patent Document 2: Japanese Laid-Open Patent Application No. 2006-306042
Patent Document 2 discloses management of an amount of waste liquid using a memory for storing information of an amount of waste liquid. Thus, even if one applies the technique of Patent Document 2 to the technique of Patent Document 1 to make the waste liquid tank replaceable, an accurate amount of waste liquid retained in the waste liquid tank cannot be known if the waste liquid tank has been replaced by a used waste liquid tank, which raises a problem that the waste liquid tank is filled up and the waste liquid may overflow.